Addressing Climate Change

Overview

Secretary of the Interior Ken Salazar released a report in April 2011 that assesses climate changes during the 21st century and how these might impact water operations, hydropower, flood control, and fish and wildlife in the western United States. The report to Congress, prepared by the Bureau of Reclamation, represents the first consistent and coordinated assessment of risks to future water supplies across Reclamation river basins, including those in the Mid-Pacific Region.

Reclamation is assessing climate change and adaptation strategies for several river basins, including California’s Sacramento Valley, below, and San Joaquin Valley, right. Photos by Robert Campbell, left, and Sara Kling.

Reclamation’s SECURE Water Act Report identified the following likely climate changes, on average annually, in the Region:

Sacramento and San Joaquin River Basins

Sacramento and San Joaquin River Basins

Temperatures are projected to increase by about 5-6 degrees by the end of the 21st century, with precipitation slightly increasing in California’s northern Central Valley and slightly decreasing in the southern Central Valley. The projections also suggest precipitation in the Sacramento and San Joaquin River basins will remain relatively similar over the next century with a slight increase of about 1 percent over the Sacramento River Basin by 2050 and a decrease of about 4 percent over the San Joaquin River Basin by 2050.

Runoff is projected to increase slightly during the first half of the 21st century and decline slightly in the latter half of the century.

As the climate warms, more precipitation falling as rain instead of snow at lower elevations will increase winter runoff and decrease summer runoff. The increase in temperature also will result in significantly decreased snowpack at higher elevations.

Klamath River Basin

Temperatures in the Klamath River Basin in southern Oregon and northern California may increase by about 5–6 degrees during the 21st century, with a projected increase of about 2 percent in precipitation by 2050.

Klamath River Basin

Runoff is projected to increase anywhere from 3-10 percent by 2050.

Increased warming is expected to reduce snowpack and snowmelt, resulting in less runoff during the late spring through early autumn. Snowpack decreases are projected to be more substantial in the warmer parts of the basin.

Truckee River Basin

Temperatures in the Truckee River Basin in the Sierra Nevada Mountains of California and Nevada are projected to increase about 3–5 degrees during the 21st century, with a decrease in precipitation of about 1 percent by 2050.

During Fiscal Year 2011, three studies have been initiated that address climate change concerns in the major Region river basins identified in the Secure Water Act of 2009. For more information on the basin studies:

Several of the WaterSMART Program climate tool matching grants that were announced in 2011 should benefit the Region’s climate change assessment and adaptation strategy planning capabilities. These include grants to the Desert Research Institute to develop tools to better simulate the effects of global climate changes in the Sierra Nevada regions, as well as improvements in methods of quantifying agricultural water needs.

More information: http://www.usbr.gov/WaterSMART/bsp/

West-wide Climate Risk Assessments will establish a foundation for more in-depth analyses and the development of adaptation options through basin studies, operations planning and other activities.

More information: http://www.usbr.gov/WaterSMART/wcra/index.html

The Region is conducting other planning studies that will include assessments of the effects of climate changes. These include the Bay Delta Conservation Plan, CALFED Bay-Delta Program storage project investigations and the Central Valley Project Integrated Resource Plan.